Dissipative convective structures and nanoparticles encapsulation in Cu/alginate/dextran composite hydrogels and sponges

A novel approach is presented to produce ordered capillaries by dissipative convective process followed by freeze drying of anisotropically ordered alginate–dextran hydrogels produced by ionic diffusion of Cu2+ ions. The ionotropic gels consisted of capillaries, 10–100 μm in diameter which comprised small pores, 10–30 μm in size. Dextran-functionalized iron or gold nanoparticles can be readily incorporated into the gels with retention of its stability and patterned microstructures. The freeze-dried Cu/alginate/dextran gel was further cross-linked with epichlorohydrin in basic media to protect its internal microstructures. Mechanical strength of the anisotropically ordered Cu/alginate/dextran sponges also investigated.